CN101281713A - Driving apparatus of display device, display device and method of driving display device - Google Patents

Abstract

The present invention provides a driving apparatus of a display device, a display device including the same, and method of driving the display device. The driving apparatus of a display device calculates a slope using a minimum gray, a maximum gray, a gray average of frame data in a current frame, and a gray average of frame data in a previous frame, and corrects and outputs the input frame data according to the slope, using frame data of one frame. As a result, a gray range of the input image signal can be extended, thereby improving visibility. Further, in a case of a motion picture, even when a difference of a gray range of images of adjacent frames is large, an original image is not distorted due to extension of a gray range. Also, even when noise is included in the input image signal, a gray range can be extended after removing the noise.

Description

The driving arrangement of display device, display device and driving method thereof

The application requires to be submitted on April 3rd, 2007 right of priority of the 10-2007-0032905 korean patent application of Korea S Department of Intellectual Property, and this application is disclosed in this for reference.

Technical field

The present invention relates to a kind of display device driving arrangement, comprise the display device of this driving arrangement and the method that drives this display device.More particularly, the present invention relates to a kind of display device the driving arrangement that improves its visuality (visibility), comprise the display device of this driving arrangement and the method that drives this display device.

Background technology

At present, replace heavy cathode ray tube (CRT), developing flat-panel monitor energetically, as Organic Light Emitting Diode (OLED) display, plasma display (PDP) and LCD (LCD).

PDP is the device that a kind of plasma that utilizes gas discharge to produce comes character display or image, and the OLED display utilizes the electroluminescence of specific organic material or polymkeric substance to come character display or image.LCD by electric field is applied to place two between the display panel liquid crystal layer and the intensity of regulating electric field, regulate the transmissivity that light passes liquid crystal layer, thereby obtain desired images.

Flat-panel monitor has and is used for processing signals so that the signal controller of display image.This signal controller changes image by handling received image signal with suitable form, with display image on display device.

In this case, the picture signal that is input to each frame of signal controller is not generally used all gray scales (gray) that can be shown, and tonal range (gray range) also is limited to preset range.In addition, when gray-scale displayed scope during to lopsidedness, image is shown secretly or is bright, thereby reduces visual.

Particularly, under the situation of motion picture since such dark image and bright image can be in short time period Alternation Display, so be difficult to recognition image.

Summary of the invention

Exemplary embodiment of the present invention provides a kind of driving arrangement of display device, this driving arrangement comprises: the tonal range computing unit, calculate the present image signal or the present image signal is carried out low-pass filtering and the minimal gray and the maximum gray scale of the signal that obtains, wherein, the described present image signal picture signal that is present frame; The transformed variable computing unit comes the computational transformation variable based on the average gray of the minimal gray of present image signal, maximum gray scale, average gray and previous picture signal, and wherein, described previous picture signal is the picture signal of previous frame; The output signal generator produces output image signal by according to described transformed variable the present image signal being carried out conversion.

Described conversion can be to use the linear transformation of slope as transformed variable.Described slope can change according to the slope of previous picture signal.

Described slope S c can be provided by following equation:

$\mathrm{Sc}=(1-|\frac{\mathrm{AGc}-\mathrm{AGp}}{G\max }\left|\right)\×\mathrm{Sp}+\left|\frac{\mathrm{AGc}-\mathrm{AGp}}{G\max }\right|\×\frac{G\max }{\mathrm{Max}-\mathrm{Min}},$

Wherein, AGc is the average gray of present frame, and AGp is the average gray of previous frame, and Gmax is the maximum gradation value that can be shown, and Sp is the slope of previous frame, and Max is the maximum gray scale of present frame, and Min is the minimal gray of present frame.

Described slope S c can have about 1 to about 2.5 value.

Described conversion can be by D '=(D-Min) Sc+c definition, and wherein, D is the present image signal, and D ' is an output image signal, and c is a constant.Described constant c can be identical with the minimal gray Min of present frame.

Low-pass filtering can comprise that the present image signal of considering neighbor proofreaies and correct the present image signal of each pixel.

Described transformed variable computing unit can comprise: average gray computing unit, the average gray of computed image signal; First memory, the storage average gray; α value computing unit comes alpha value calculated with the difference of the average gray of previous picture signal divided by the maximum gradation value that can be shown by the average gray with the present image signal; Basic slope calculation unit SCU is calculated basic slope by the maximum gradation value that can be shown divided by the difference of described maximum gray scale and minimal gray; Slope calculation unit SCU is calculated the slope of present image signal based on the slope of α value, basic slope and previous picture signal; Second memory is stored in the slope that calculates in the slope calculation unit SCU, and the slope of previous picture signal is offered slope calculation unit SCU.

Described output signal generator can comprise: frame memory, storage present image signal; Adjustment of data unit carries out linear transformation according to the slope that receives from slope calculation unit SCU to the present image signal that receives from frame memory, thereby produces output image signal.

Described tonal range computing unit can comprise: low-pass filter removes noise by the present image signal is carried out low-pass filtering; Minimal gray and maximum gray scale computing unit calculate minimal gray and maximum gray scale through the present image signal of low-pass filter.Described low-pass filter can be by to predefined weight being provided and it is proofreaied and correct the present image signal of each pixel in the Calais mutually with the present image signal of the present image signal adjacent pixels of each pixel.

Other exemplary embodiment of the present invention provides a kind of method that drives display device, and this method comprises: calculate the minimal gray and the maximum gray scale of present image signal, wherein, described present image signal is the picture signal of present frame; Calculate the average gray of present image signal; Average gray based on the minimal gray of present image signal, maximum gray scale, average gray and previous picture signal comes slope calculations, and wherein, described previous picture signal is the picture signal of previous frame; Based on described slope the present image signal is carried out linear transformation.

The step of slope calculations can comprise: come alpha value calculated with the difference of the average gray of previous picture signal divided by the maximum gradation value that can be shown by the average gray with the present image signal; By described maximum gradation value is calculated basic slope divided by the difference of described maximum gray scale and minimal gray; Slope based on α value, basic slope and previous picture signal calculates described slope.

Described slope S c can be provided by Sc=(1-α) * Sp+ α * Sb, and wherein, Sp is the slope of previous picture signal, and Sb is basic slope.

Linear transformation can be satisfied the Sc+c of D '=(D-min), and wherein, D is the present image signal, and D ' is an output image signal, and min is a minimal gray, and c is a constant.Described constant c can be identical with minimal gray min.

Described method also can comprise: before calculating minimal gray and maximum gray scale, remove the noise that exists in the present image signal.The step of removing noise can comprise: by providing weight to the picture signal adjacent with each present image signal and its addition being removed the noise of each present image signal.

Other exemplary embodiment of the present invention provides a kind of display device, comprise: signal controller, by producing output image signal based on average gray, minimal gray and the maximum gray scale of present image signal and the average gray correction present image signal of previous picture signal, wherein, described present image signal is the picture signal of present frame, and described previous picture signal is the picture signal of previous frame; Data driver is transformed to data voltage with output image signal; Display panel receives data voltage with display image.

Described signal controller can be transformed to output image signal with present image signal linearity based on slope S c, wherein, described slope S c is based on the average gray calculating of the minimal gray of present image signal, maximum gray scale, average gray and previous picture signal.Described slope S c can change according to the slope of previous picture signal.

Described slope S c can be provided by following equation:

$\mathrm{Sc}=(1-|\frac{\mathrm{AGc}-\mathrm{AGp}}{G\max }\left|\right)\×\mathrm{Sp}+\left|\frac{\mathrm{AGc}-\mathrm{AGp}}{G\max }\right|\×\frac{G\max }{\mathrm{Max}-\mathrm{Min}},$

Wherein, AGc is the average gray of present frame, and AGp is the average gray of previous frame, and Gmax is the maximum gradation value that can be shown, and Sp is the slope of previous frame, and Max is the maximum gray scale of present frame, and Min is the minimal gray of present frame.

Conversion can be by D '=(D-Min) Sc+Min definition, and wherein, D is the present image signal, and D ' is an output image signal.

Description of drawings

By the description of carrying out below in conjunction with accompanying drawing, can understand exemplary embodiment of the present invention in more detail, wherein:

Fig. 1 is the block diagram of example LCD (LCD) according to an exemplary embodiment of the present invention;

Fig. 2 is the equivalent circuit diagram of the example pixel in example LCD according to an exemplary embodiment of the present invention;

Fig. 3 is that the example image quality improves the block diagram of unit according to an exemplary embodiment of the present invention;

Fig. 4 is the histogram of the picture signal of a frame in exemplary embodiment of the present;

Fig. 5 is the curve map that is illustrated in the relation between the input gray level and output gray level in the exemplary embodiment of the present invention;

Fig. 6 illustrates the slope of frame data of Fig. 5 and the curve map of the relation between output digital image signal DAT and the input gray level;

Fig. 7 is the block diagram of example tonal range computing unit according to an exemplary embodiment of the present invention;

Fig. 8 illustrates example low-pass filtering mask according to an exemplary embodiment of the present invention;

Fig. 9 illustrates according to an exemplary embodiment of the present invention the situation that example low-pass filtering mask (mask) and example liquid crystal panel assembly is applied to each pixel.

Embodiment

The invention provides a kind of display device driving arrangement, comprise the display device of this driving arrangement and drive the method for this display device that its advantage is: the tonal range by the expansion received image signal is improved visuality.The present invention also provide a kind of display device driving arrangement, comprise the display device of this driving arrangement and drive the method for this display device, its advantage is: under the situation of motion picture, even when the tonal range between the image of consecutive frame differs greatly, because the expansion of tonal range also can prevent the generation of image fault.The present invention also provide a kind of display device driving arrangement, comprise the display device of this driving arrangement and drive the method for this display device that its advantage is: even when in received image signal, comprising noise, also after removing noise, expand tonal range.

In the present invention, utilize the average gray of previous frame, the average gray of present frame, the slope (slope) of previous frame and the minimum gradation value and the maximum gradation value of present frame to expand tonal range.

Below, the present invention is described with reference to the accompanying drawings more fully, exemplary embodiment of the present invention has been shown in the accompanying drawing.It should be appreciated by those skilled in the art that described embodiment can revise in various mode under the situation that does not break away from the spirit and scope of the present invention.

In the accompanying drawings, exaggerated the thickness in layer, film, panel, zone etc. for clarity.Run through instructions, identical label is represented identical parts.Should be appreciated that when the element such as layer, film, zone or substrate is known as when being positioned on another element, this element can be located immediately on another element, perhaps also can have intermediary element.On the contrary, when element is known as when being located immediately on another element, there is not intermediary element.As used herein, term " and/or " comprise one or more relevant arbitrary combinations of being listd and all make up.

It should be understood that, describe various elements, assembly, zone, layer and/or part though can use term " first ", " second ", " the 3rd " to wait here, these elements, assembly, zone, layer and/or part are not limited by these terms should.These terms just are used for an element, assembly, zone, layer or part and another element, assembly, zone, layer or part are distinguished.Therefore, under the situation that does not break away from instruction of the present invention, first element of discussing below, assembly, zone, layer or part can be known as second element, assembly, zone, layer or part.

Term used herein is for the purpose of describing specific embodiment, and is not intended to restriction the present invention.As used herein, unless clearly expression in addition in the context, singulative is intended to also comprise plural form.It should also be understood that, when in instructions, using term " to comprise " and/or when " comprising ", it shows the existence of described feature, zone, integral body, step, operation, element and/or assembly, and does not get rid of existence or add one or more further features, zone, integral body, step, operation, element, assembly and/or their group.

For convenience, here can the usage space relative terms such as " ... following ", " ... following ", " following ", " ... more than ", " top " wait element describing shown in accompanying drawing or the relation between feature and other element or the feature.It should be understood that also comprise the orientation that the space relative terms is intended to describe in comprising accompanying drawing device use or operation in different azimuth.For example, if with the device in accompanying drawing upset, then be described to " " other element or feature " following " or " below " element will be positioned as thereupon " " other element or feature " more than ".Therefore, for example, term " ... following " can comprise " ... more than " and " ... following " two orientation.Also can be with device in addition location (revolve turn 90 degrees or with other orientation), and should respective explanations space used herein relative descriptors.

Unless otherwise defined, otherwise the implication of all terms used herein (comprising technical term and scientific terminology) is identical with the implication of those skilled in the art's common sense.It should also be understood that, term (such as the term that defines in general dictionary) should be understood that their implication is consistent in the environment of its implication and association area, unless and specifically defined, otherwise should not explain these terms here with idealized or too formal implication.Below, the present invention is described with reference to the accompanying drawings in more detail.

At first, see figures.1.and.2, describe LCD (LCD) according to an exemplary embodiment of the present invention in detail.

Fig. 1 is the block diagram of example LCD according to an exemplary embodiment of the present invention, and Fig. 2 is the equivalent circuit diagram of the example pixel among the example LCD according to an exemplary embodiment of the present invention.

LCD comprises liquid crystal panel assembly 300, gate drivers 400, data driver 500, grayscale voltage generator 800 and signal controller 600 according to an exemplary embodiment of the present invention.Signal controller 600 comprises the image quality raising unit 610 that is used to improve image quality.

With reference to Fig. 1, from the equivalent electrical circuit angle, liquid crystal panel assembly 300 comprises many signal line G ₁-G _nAnd D ₁-D _mAnd be connected to described many signal line and be arranged in a plurality of pixel PX of approximate matrix form.From structure angle shown in Figure 2, liquid crystal panel assembly 300 comprises lower panel 100 respect to one another and top panel 200 and places liquid crystal layer 3 between the upper and lower panel.

Signal wire G ₁-G _nAnd D ₁-D _mComprise many gate lines G that are used to transmit signal (being also referred to as " sweep signal ") ₁-G _nWith many data line D that are used to transmit data voltage ₁-D _mGate lines G ₁-G _nBe similar to go up and extend and substantially parallel to each other data line D at line direction (as, first direction) ₁-D _mBe similar to go up and extend and substantially parallel to each other at column direction (as, second direction).First direction can be vertical substantially each other with second direction.

Each pixel PX, for example be connected to i (i=1,2 ..., n) gate lines G _iWith j (j=1,2 ..., m) data line D _jPixel PX, comprise being connected to signal wire G _iAnd D _jOn-off element Q and the liquid crystal capacitor C that is connected to on-off element Q _LCWith holding capacitor C _STIn optional exemplary embodiment, when needs, holding capacitor C _STCan omit.

On-off element Q is arranged on the three-terminal element (as thin film transistor (TFT) (TFT)) in the lower panel 100, and its control end (as grid) is connected to data line G _i, its input end (as source electrode) is connected to data line D _j, its output terminal (as drain electrode) is connected to liquid crystal capacitor C _LCWith holding capacitor C _ST

Liquid crystal capacitor C _LCAs two ends, the liquid crystal layer 3 between two electrodes 191 and 270 is as dielectric material (dielectricmaterial) with the common electrode 270 of the pixel electrode 191 of lower panel 100 and top panel 200.Pixel electrode 191 is connected to the output terminal of on-off element Q, and common electrode 270 is formed on the whole surface of top panel 200, on the perhaps whole substantially surface, is used to receive common-battery and presses V _ComIn optional exemplary embodiment, different with the situation of Fig. 2, common electrode 270 can be arranged in the lower panel 100, and in this case, at least one in two electrodes 191 and 270 can form linear or bar shaped.

As liquid crystal capacitor C _LCThe holding capacitor C of auxiliary element _STBy forming such as the independent signal wire (not shown) of storage electrode line and the overlapping of pixel electrode 191 that is arranged in the lower panel 100, and insulator places between described independent signal wire and the pixel electrode 191, and predetermined voltage is (as common-battery pressure V _Com) be applied to described independent signal wire.Yet, holding capacitor C _STCan be by pixel electrode 191 and the last gate lines G that is located immediately at through insulator on the electrode 191 _I-1Overlapping formation.

In order to show colored the demonstration, by making each pixel PX a kind of color (spatial division) concentrated of Show Color or Show Color collection (time division) alternately successively inherently, the room and time by color makes up discerns desired color.The example of color set can comprise primary colors, and can comprise redness, green and blue.Fig. 2 shows the example of spatial division, and wherein, each pixel PX is provided with the color filter 230 that is used to show a kind of color in the zone corresponding with pixel electrode 191 of plate 200 in the above.In optional exemplary embodiment, different with the situation of Fig. 2, color filter 230 can be formed on the pixel electrode 191 of lower panel 100 or under.

At liquid crystal panel assembly 300 places at least one polarizer (not shown) is set.In the exemplary embodiment, on plate 100 and the top panel 200 the first polarizing coating (not shown) and the second polarizing coating (not shown) are set respectively below.First polarizing coating and second polarizing coating can be regulated the optical transmission direction that is provided to from the outside lower panel 100 and the top panel 200 respectively according to the direction of orientation of liquid crystal layer 3.First polarization axle of first polarizing coating can be vertical substantially each other with second polarization axle of second polarizing coating.

Refer again to Fig. 1, grayscale voltage generator 800 produces all grayscale voltages, the grayscale voltage of perhaps relevant with the transmissivity of pixel PX fixed qty (below, be called " reference gray level voltage ").Grayscale voltage can comprise with respect to common-battery presses V _ComHave on the occasion of voltage and press V with respect to common-battery _ComVoltage with negative value.

Gate drivers 400 is connected to the gate lines G of liquid crystal panel assembly 300 ₁-G _n, be used for and comprise gate-on voltage V _OnWith grid cut-off voltage V _OffThe signal of combination be applied to gate lines G ₁-G _n

Data driver 500 is connected to the data line D of liquid crystal panel assembly 300 ₁-D _m, be used to select grayscale voltage, and this grayscale voltage be applied to data line D as data voltage from grayscale voltage generator 800 ₁-D _mYet when grayscale voltage generator 800 only provides the reference gray level voltage of fixed qty, but not when all grayscale voltage was provided, data driver 500 produced desired data voltage by reference gray level voltage is carried out dividing potential drop.

Signal controller 600 control gate drivers 400 and data driver 500, signal controller 600 comprise the image quality raising unit 610 that is used to improve contrast.Will be further described below detailed structure and operation that image quality improves unit 610.

In the drive unit 400,500,600 and 800 each can be directly installed on the liquid crystal panel assembly 300 with the form of at least one integrated circuit (IC) chip.In addition, each in the drive unit 400,500,600 and 800 can be installed on flexible print circuit (FPC) the film (not shown) that will be attached to liquid crystal panel assembly 300 with the form of band year encapsulation (TCP).In the drive unit 400,500,600 and 800 each can be installed on independent printed circuit board (PCB) (PCB) (not shown).Alternatively, drive unit 400,500,600 and 800 is together with signal wire G ₁-G _nAnd D ₁-D _mAnd TFT on-off element Q can form as one with liquid crystal panel assembly 300 together.In addition, drive unit 400,500,600 and 800 can be integrated in the single chip, in this case, at least one circuit component of at least one in the drive unit 400,500,600 and 800 or formation drive unit 400,500,600 and 800 can be disposed in the outside of this single chip.

Now, the operation of LCD will be further described.

The input control signal that signal controller 600 receives received image signal R, G and B and is used to control the demonstration of received image signal R, G and B from the external graphics controller (not shown).Received image signal R, G and B comprise brightness (luminance) information of each pixel PX, and brightness has the gray scale to determined number, and for example 1024 (=2 ¹⁰), 256 (=2 ⁸) or 64 (=2 ⁶) individual gray scale.In exemplary embodiment of the present invention, the example with 256 gray scales is described.Input control signal comprises for example vertical synchronizing signal V _Sync, horizontal-drive signal H _Sync, master clock signal MCLK and data enable signal DE.

Signal controller 600 is based on received image signal R, G and B and input control signal, service condition according to liquid crystal panel assembly 300 is suitably handled received image signal R, G and B, and produces grid control signal CONT1 and data controlling signal CONT2 based on input control signal.Afterwards, signal controller 600 sends to gate drivers 400 with grid control signal CONT1, and the data image signal DAT after data controlling signal CONT2 and the processing is sent to data driver 500.

Specifically, as will be further described below, image quality improves unit 610 and proofreaies and correct received image signal R, G and B according to the minimal gray of received image signal R, G and B and the transformed variable (conversion variable) of maximum gray scale and definition suitably.

Grid control signal CONT1 comprises and is used for the scanning commencing signal STV that beacon scanning begins and is used to control gate-on voltage V _OnAt least one clock signal in output cycle.Grid control signal CONT1 also can comprise and is used to limit gate-on voltage V _OnThe output enable signal OE of duration.

Data controlling signal CONT2 comprises: horizontal synchronization commencing signal STH is used to notify the transmission of the data image signal DAT of one-row pixels PX to begin; Load signal LOAD and data clock signal HCLK are used for analog data voltage is applied to data line D ₁-D _mData controlling signal CONT2 also can comprise reverse signal RVS, is used for data voltage is pressed V with respect to common-battery _ComPolarity (below, will " polarity that data voltage is pressed with respect to common-battery " be called " polarity of data voltage ") counter-rotating.

Data driver 500 receives the data image signal DAT that is used for one-row pixels PX according to the data controlling signal CONT2 from signal controller 600, corresponding to the grayscale voltage of each data image signal DAT selection from grayscale voltage generator 800, thereby DAT is transformed to analog data voltage with data image signal, then this analog data voltage is applied to corresponding data line D ₁-D _m

Gate drivers 400 according to from the grid control signal CONT1 of signal controller 600 with gate-on voltage V _OnBe applied to gate lines G ₁-G _n, so that be connected to gate lines G ₁-G _nOn-off element Q conducting.Therefore, be applied to data line D ₁-D _mThe on-off element Q of data voltage by conducting be applied to corresponding pixel PX.

The common-battery that is applied to the common electrode of top panel 200 is pressed V _ComShow as liquid crystal capacitor C with the difference of the data voltage that is applied to pixel PX _LCCharge voltage, i.e. pixel voltage.The liquid crystal molecule of liquid crystal layer 3 changes their arrangement according to the size of pixel voltage, changes so that pass the polarisation of light of liquid crystal layer 3.The change of polarization shows as the change of polarizer to the optical transmission rate, thereby pixel PX shows the brightness of the gray scale that embodies data image signal DAT.

By repeating said process, gate-on voltage V for unit with a horizontal cycle (being called " 1H ", identical) with the one-period of horizontal-drive signal Hsync and data enable signal DE _OnBe applied to all gate lines G successively ₁-G _n, data voltage is applied to all pixel PX, thereby shows the image of a frame.

Be applied to the state Be Controlled of the reverse signal RVS of data driver 500, so that next frame is when a frame end, and be applied to the polarity and polarity opposite (" frame counter-rotating ") the previous frame of the data voltage of each pixel PX from data driver 500.Even in a frame, according to the characteristic of reverse signal RVS, the polarity that flows through the data voltage of a data line can be by periodic variation (for example, row counter-rotating and some counter-rotating), the polarity that perhaps is applied to the data voltage of a pixel column can differ from one another (for example, row counter-rotatings and some counter-rotating).

Below, describing according to an exemplary embodiment of the present invention, image quality improves the structure of unit 610 and the processing of received image signal R, G and B.

Fig. 3 is that the example image quality improves the block diagram of unit according to an exemplary embodiment of the present invention, and Fig. 4 is the histogram of the picture signal of a frame in exemplary embodiment of the present invention.Fig. 5 is the curve map that is illustrated in the relation between the input gray level and output gray level in the exemplary embodiment of the present invention, and Fig. 6 is the curve map that is illustrated in the relation between the input gray level and output gray level in another exemplary embodiment of the present invention.

Image quality raising unit 610 comprises slope calculation unit SCU 620, output signal generator 630, tonal range computing unit 640 and receiving element 650 according to an exemplary embodiment of the present invention.Image quality improves unit 610 and comes conversion received image signal R, G and B according to the transformed variable that is used for the picture signal of a frame, determines described transformed variable based on the average gray and the transformed variable of minimum gray value, gray scale maximal value and the average gray and the previous frame of this frame.Specifically, described conversion is linear transformation, and described transformed variable is corresponding to the slope of linear transformation.

Slope calculation unit SCU 620 (also can be called as the transformed variable computing unit) comprises average gray computing unit 621, first memory 622, α value computing unit 623, basic slope calculation unit SCU 624, slope calculation unit SCU 625 and second memory 626.Output signal generator 630 comprises frame memory 631 and adjustment of data unit 632.

Receiving element 650 receives and is input to received image signal R, G and the B that image quality improves unit 610, and received image signal R, G and B are outputed to slope calculation unit SCU 620, output signal generator 630 and tonal range computing unit 640.

The minimum value and the maximal value of the gray scale of tonal range computing unit 640 calculating input image signal R, G and B.More particularly, tonal range computing unit 640 has the storage space that is used to store maximum gradation value and minimum gradation value, 640 storages of tonal range computing unit at first are input to the gray scale of the picture signal of this storage space, received image signal R, G that will import successively then and B and the value that is stored in the storage space compare, and upgrade described value.As received image signal R, G and the B for a frame, when such process finished, the maximum gradation value of frame and minimum gradation value were stored in the storage space of tonal range computing unit 640.

As shown in Figure 4, available histogram is represented maximum gradation value and minimum gradation value.Histogram is the curve map of frequency that shows each gray scale of received image signal R, G and B.In the curve of Fig. 4, minimum gradation value is " b ", and maximum gradation value is " a ".Below, the minimum gradation value of received image signal R, G that calculates in tonal range computing unit 640 and the gray scale of B is " b ", maximum gradation value is " a ".

Tonal range computing unit 640 offers slope calculation unit SCU 620 with minimum value b and the maximal value a that calculates, and minimum value b also is exported to output signal generator 630.

The mean value of average gray computing unit 621 calculating input image signal R, G and B (below, be called " average gray cur_avg ").For example, as the n * m that adds up to of pixel, and the received image signal of pixel PX is D _IjThe time, the average gray cur_avg of received image signal is by equation 1 expression.

(equation 1)

$\mathrm{cur}\_\mathrm{avg}=\frac{\underset{i,j}{\mathrm{\Σ}}{D}_{\mathrm{ij}}}{n\×m}$

First memory 622 receives the average gray cur_avg that calculates, and stores this value till next frame.Therefore, if import new average gray cur_avg, then the average gray of first memory 622 output storages is as the average gray prev_avg of previous frame.

α value computing unit 623 utilizes the average gray cur_avg of the present frame that receives from average gray computing unit 621 and the average gray prev_avg of the previous frame that receives from first memory 622 comes alpha value calculated.The α value is by equation 2 definition.

(equation 2)

$\mathrm{\&alpha;}=\left|\frac{\mathrm{cur}\_\mathrm{avg}-\mathrm{prev}\_\mathrm{<figure-callout\; id="255"\; label="avg"\; filenames="A20081007411100251.png"\; state="\{\{state\}\}">avg</figure-callout>}}{255}\right|$

Here, owing to be maximal value, subtract 1 so equal total grey as the number of denominator since the gray scale that can be shown of the 0th gray scale as the number of denominator.In equation 2, in the exemplary embodiment of considering 256 gray scales, denominator is set to 255.The α value of calculating by equation 2 has 0 to 1 value.The α value is by the difference of the average gray prev_avg of the average gray cur_avg of present frame and the previous frame maximal value divided by gray scale is obtained, and represents two mean luminance differences between the frame.

Basic slope calculation unit SCU 624 utilizes minimum gradation value b and maximum gradation value a to calculate the basic slope basic_slope that is defined by equation 3.

(equation 3)

$\mathrm{basic}\_\mathrm{slope}=\frac{255}{a-b}$

Wherein, the number of molecule is the maximal value of the gray scale that can be shown, and under the situation of 256 gray scales, this number is 255.

The basic slope basic_slope that slope calculation unit SCU 625 is calculated from the α value that provided by α value computing unit 623, by basic slope calculation unit SCU 624 and calculate slope by equation 4 definition from the first front slope prev_slope of second memory 626.

(equation 4)

slope＝(1-α)prev_slope+(α)basic_slope

Wherein, first front slope (prev_slope) is the slope of the picture signal of previous frame, and is the value that is stored in the second memory 626.

That is, $\mathrm{slope}=(1-|\frac{\mathrm{cur}\_\mathrm{avg}-\mathrm{prev}\_\mathrm{<figure-callout\; id="255"\; label="avg"\; filenames="A20081007411100251.png"\; state="\{\{state\}\}">avg</figure-callout>}}{255}\left|\right)\&times;\mathrm{prev}\_\mathrm{slope}+\left|\frac{\mathrm{cur}\_\mathrm{avg}-\mathrm{prev}\_\mathrm{<figure-callout\; id="255"\; label="avg"\; filenames="A20081007411100251.png"\; state="\{\{state\}\}">avg</figure-callout>}}{255}\right|\&times;\frac{255}{a-b}$

Slope calculation unit SCU 625 is stored in the slope that calculates in the second memory 626, and when the slope of the picture signal of calculating next frame, second memory 626 provides the slope prev_slope of this slope as previous frame.

Output signal generator 630 comprises frame memory 631 and adjustment of data unit 632.

Received image signal R, G and B that frame memory 631 storages receive from receiving element 650.

Adjustment of data unit 632 carries out linear transformation to produce output digital image signal DAT according to the rule that is provided by equation 5 to the received image signal that receives from frame memory 631.

(equation 5)

DAT＝(Frame_Data-b)slope+c

Wherein, c is constant and has 0 to 255 value.For example, c can be set to minimum gradation value b.

Fig. 6 illustrates equation 5 (wherein, the curve map of relation c=b).

If the gray scale of received image signal (below, be called " input gray level ") be minimum gradation value b, then the gray scale of output image signal DAT (below, be called " output gray level ") also is " b ", and along with input gray level increases, output gray level also increases according to slope.If input gray level is maximum gradation value a, then output gray level also becomes maximal value MAX.Yet when calculating by equation 5, the maximal value MAX of output gray level may surpass the maximal value of the gray scale that can be shown, for example 255.In this case, the clamper value is set to 255.Because human eye can not be discerned the luminance difference greater than predeterminated level, so even carried out clamper, also no problem aspect recognition image.

In the superincumbent description, the constant c of equation 5 is set to equal the minimum gradation value b of input gray level, so that display brightness is set to greater than minimum gradation value b.

May be by the slope that equation 4 calculates less than 1.In this case, because the scope of input gray level becomes less than the scope of output gray level, so contrast is not expanded.Therefore, the minimum value of slope preferably is fixed to 1.Preferred slope is about 2.5 or littler, particularly when the value of slope be about 2 the time, the image enhancement works very well.

Specifically, when slope calculations, owing to except the brightness of present frame, also considered the brightness of previous frame, so even the luminance difference of consecutive frame is bigger, the image of demonstration can distortion yet.

When display operation began, in order to handle received image signal R, G and the B of at first input, initial value can be stored in first memory 622 and the second memory 626.After display device starts, need a certain amount of time could show normal picture,, can obtain stable output image signal by in the certain hour section, some frames being carried out data processing, therefore, the initial value that is stored in first memory 622 and the second memory 626 can have random value.

Fig. 5 illustrates wherein that the output gray level of the minimum gradation value b of input gray level is 0, and the output gray level of the maximum gradation value a of input gray level is the curve map of 255 relation, and it is illustrated to be used for comparison.

Except image quality improved the signal Processing of unit 610, signal controller 600 also can be carried out other signal Processing, as dynamic capacitance compensation (DCC) and adaptive color correction (ACC).

With reference to Fig. 7 to Fig. 9, describe tonal range computing unit 640 according to an exemplary embodiment of the present invention in detail.

Fig. 7 is the block diagram of example tonal range computing unit according to an exemplary embodiment of the present invention, Fig. 8 illustrates example low-pass filtering mask according to an exemplary embodiment of the present invention, and Fig. 9 illustrates according to an exemplary embodiment of the present invention the situation that example low-pass filtering mask and example liquid crystal panel assembly is applied to each pixel.

As shown in Figure 7, the tonal range computing unit 640 according to current exemplary embodiment comprises low-pass filter 641 and minimal gray (b) and maximum gray scale (a) computing unit 642.

Low-pass filter 641 is removed the noise that exists in the received image signal.When comprising noise in the received image signal, minimum gradation value of calculating (b) and maximum gradation value (a) be owing to noise changes, and noise can clearly be shown, therefore utilizes low-pass filter 641 to remove noise.

For example, low-pass filter 641 comprises mask 900 as shown in Figure 8.The zone of cutting apart on the mask 900 (below, be called " cut zone ") is corresponding to the pixel PX of liquid crystal panel assembly 300, and as shown in Figure 8,7 * 7 cut zone is set on mask 900, but also can use the cut zone of optional quantity on the mask 900.In addition, mask 900 has central area o, and (for example, minimum 1/256, maximum 40/256) assigns weight in each cut zone of mask 900.O is far away more in cut zone decentering zone, and cut zone has more little weight, and all weight sums of mask 900 are 1.

Fig. 9 illustrates the application principle of mask 900.When mask 900 is applied to the received image signal of specific pixel, the central area o of mask 900 is arranged to corresponding with this specific pixel, the weight of each cut zone on the mask 900 and picture signal corresponding to the pixel of cut zone are multiplied each other, then with the value addition of all acquisitions.Income value is called as filtering image signal D _Ij',, and by equation 6 expressions.

(equation 6)

${D^{\&prime;}}_{\mathrm{ij}}=\underset{\mathrm{ij}}{\mathrm{\&Sigma;}}{\mathrm{MK}}_{\mathrm{ij}}\&times;D_{\mathrm{ij}}$

Wherein, D _IjValue is the received image signal of pixel, MK _IjBe on the mask 900 with D _IjThe weight of corresponding divided areas.In not corresponding pixel with the cut zone of mask 900, MK _IjBe considered to 0.

With reference to Fig. 8 and Fig. 9, an example is described.

At first, suppose that the overlapping pixel of center o with mask 900 is the j pixel o ' of first row, around the received image signal D of several pixels of j pixel o ' _IjGray-scale value as shown in table 1.

(table 1)

	(j-3) row	(j-2) row	(j-1) row	The j row	(j+1) row	(j+2) row	(j+3) row
								The 1st row	31	34	15	230 (o′)	12	30	31
The 2nd row	38	21	12	18	23	40	58
								The 3rd row	29	6	41	13	41	30	61
The 4th row	110	213	130	210	180	130	98

Filtering image signal D _Ij' as follows.

D ' _Ij=31 * 1/256+34 * 4/256+15 * 16/256+230 * 40/256+12 * 16/256+30 * 4/256+31 * 1/256+38 * 1/256+21 * 4/256+12 * 16/256+18 * 16/256+23 * 16/256+40 * 4/256+58 * 1/256+29 * 1/256+6 * 4/256+41 * 4/256+13 * 4/256+41 * 4/256+30 * 4/256+61 * 1/256+110 * 1/256+213 * 1/256+130 * 1/256+210 * 1/256+180 * 1/256+130 * 1/256+98 * 1/256=50.09 (being reduced to 2 significant digits)

In this sample calculation, there is not pixel walking in the corresponding liquid crystal panel assembly 300 of the third line with first of mask 900.In this case, in computation process, the received image signal of each pixel corresponding with corresponding cut zone is considered to 0.

In this sample calculation, the input gray level of the pixel o ' corresponding with the center o of mask 900 is 230.Since this value than around the value of gray scale a lot of greatly, so that input gray level may be the possibility of noise is very high.In this case, if input gray level is through utilizing the low-pass filter 641 of mask 900, then the value of input gray level is corrected for and equals filtering image signal D _Ij' (in the exemplary embodiment, being 50.09), so noise disappearance, thus input gray level has and the close value of gray-scale value on every side.

By said method, in all pixels, produce filtering image signal D _Ij'.

Minimal gray (b) and maximum gray scale (a) computing unit 642 calculate and output filtering image signal D _Ij' minimum gradation value b and maximum gradation value a.

In the exemplary embodiment, LCD has been described.Yet, the invention is not restricted to LCD, but can be applicable to display device such as Organic Light Emitting Diode (OLED) display or plasma display (PDP).

As mentioned above, utilize minimal gray and maximum gray scale, the average gray of respective frame and the average gray of previous frame of the picture signal of a frame, received image signal is corrected and exports.

As a result, the tonal range of picture signal can be expanded, thereby has improved visuality.In addition, under the situation of motion picture, even the tonal range of consecutive frame differs greatly, because the expansion of tonal range, original image can distortion yet.In addition, even comprise noise in the received image signal, also can after removing noise, expand tonal range.

Although described the present invention in conjunction with actual example embodiment, should be appreciated that, the invention is not restricted to disclosed embodiment, but opposite, the invention is intended to cover various modifications and equivalent arrangements in the spirit and scope that are included in claim.

Claims (24)

1, a kind of driving arrangement of display device, this driving arrangement comprises:

The tonal range computing unit calculates the present image signal or the present image signal is carried out low-pass filtering and the minimal gray and the maximum gray scale of the signal that obtains, and wherein, described present image signal is the picture signal of present frame;

The transformed variable computing unit comes the computational transformation variable based on the average gray of the minimal gray of present image signal, maximum gray scale, average gray and previous picture signal, and wherein, described previous picture signal is the picture signal of previous frame;

The output signal generator produces output image signal by according to described transformed variable the present image signal being carried out conversion.

2, the driving arrangement of display device as claimed in claim 1, wherein, described conversion is to use the linear transformation of slope as transformed variable.

3, the driving arrangement of display device as claimed in claim 2, wherein, described slope changes according to the slope of previous picture signal.

4, the driving arrangement of display device as claimed in claim 3, wherein, described slope S c is provided by following equation:

$\mathrm{Sc}=(1-|\frac{\mathrm{AGc}-\mathrm{AGp}}{G\max }\left|\right)\&times;\mathrm{Sp}+\left|\frac{\mathrm{AGc}-\mathrm{AGp}}{G\max }\right|\&times;\frac{G\max }{\mathrm{Max}-\mathrm{Min}},$

Wherein, AGc is the average gray of present frame, and AGp is the average gray of previous frame, and Gmax is the maximum gradation value that can be shown, and Sp is the slope of previous frame, and Max is the maximum gray scale of present frame, and Min is the minimal gray of present frame.

5, the driving arrangement of display device as claimed in claim 4, wherein, described slope S c has about 1 to about 2.5 value.

6, the driving arrangement of display device as claimed in claim 4, wherein, described conversion is by D '=(D-Min) Sc+c definition, and wherein, D is the present image signal, and D ' is an output image signal, and c is a constant.

7, the driving arrangement of display device as claimed in claim 6, wherein, described constant c is identical with the minimal gray Min of present frame.

8, the driving arrangement of display device as claimed in claim 3, wherein, described transformed variable computing unit comprises:

The average gray computing unit, the average gray of computed image signal;

First memory, the average gray that storage is calculated by the average gray computing unit;

α value computing unit comes alpha value calculated with the difference of the average gray of previous picture signal divided by the maximum gradation value that can be shown by the average gray with the present image signal;

Basic slope calculation unit SCU is calculated basic slope by the maximum gradation value that can be shown divided by the difference of described maximum gray scale and minimal gray;

Slope calculation unit SCU is calculated the slope of present image signal based on the slope of α value, basic slope and previous picture signal;

Second memory is stored in the slope that calculates in the slope calculation unit SCU, and the slope of previous picture signal is offered slope calculation unit SCU.

9, the driving arrangement of display device as claimed in claim 8, wherein, described output signal generator comprises:

Frame memory, storage present image signal;

Adjustment of data unit carries out linear transformation according to the slope that receives from slope calculation unit SCU to the present image signal that receives from frame memory, thereby produces output image signal.

10, the driving arrangement of display device as claimed in claim 9, wherein, described tonal range computing unit comprises:

Low-pass filter removes noise by the present image signal is carried out low-pass filtering;

Minimal gray and maximum gray scale computing unit calculate minimal gray and maximum gray scale through the present image signal of low-pass filter.

11, the driving arrangement of display device as claimed in claim 10, wherein, described low-pass filter is by to predefined weight being provided and it is proofreaied and correct the present image signal of each pixel in the Calais mutually with the present image signal of the present image signal adjacent pixels of each pixel.

12, the driving arrangement of display device as claimed in claim 1, wherein, low-pass filtering comprises that the present image signal of considering neighbor proofreaies and correct the present image signal of each pixel.

13, a kind of method that drives display device, this method comprises:

Calculate the minimal gray and the maximum gray scale of present image signal, wherein, described present image signal is the picture signal of present frame;

Calculate the average gray of present image signal;

Average gray based on the minimal gray of present image signal, maximum gray scale, average gray and previous picture signal comes slope calculations, and wherein, described previous picture signal is the picture signal of previous frame;

Based on described slope the present image signal is carried out linear transformation.

14, method as claimed in claim 13, wherein, the step of slope calculations comprises:

Come alpha value calculated with the difference of the average gray of previous picture signal divided by the maximum gradation value that can be shown by average gray with the present image signal;

By described maximum gradation value is calculated basic slope divided by the difference of described maximum gray scale and minimal gray;

Slope based on α value, basic slope and previous picture signal calculates described slope.

15, method as claimed in claim 14, wherein, described slope S c is provided by Sc=(1-α) * Sp+ α * Sb, and wherein, Sp is the slope of previous picture signal, and Sb is basic slope.

16, method as claimed in claim 15, wherein, the Sc+c of D '=(D-min) is satisfied in linear transformation, and wherein, D is the present image signal, and D ' is an output image signal, and min is a minimal gray, c is a constant.

17, method as claimed in claim 16, wherein, described constant c is identical with minimal gray min.

18, method as claimed in claim 13 also comprises: before calculating minimal gray and maximum gray scale, remove the noise that exists in the present image signal.

19, method as claimed in claim 18, wherein, the step of removing noise comprises: by providing weight to the picture signal adjacent with each present image signal and its addition being removed the noise of each present image signal.

20, a kind of display device comprises:

Signal controller, by producing output image signal based on average gray, minimal gray and the maximum gray scale of present image signal and the average gray correction present image signal of previous picture signal, wherein, described present image signal is the picture signal of present frame, and described previous picture signal is the picture signal of previous frame;

Data driver is transformed to data voltage with output image signal;

Display panel receives data voltage with display image.

21, display device as claimed in claim 20, wherein, described signal controller is transformed to output image signal based on slope S c with present image signal linearity, wherein, described slope S c is based on the average gray calculating of the minimal gray of present image signal, maximum gray scale, average gray and previous picture signal.

22, display device as claimed in claim 21, wherein, described slope S c changes according to the slope of previous picture signal.

23, display device as claimed in claim 22, wherein, described slope S c is provided by following equation:

$\mathrm{Sc}=(1-|\frac{\mathrm{AGc}-\mathrm{AGp}}{G\max }\left|\right)\&times;\mathrm{Sp}+\left|\frac{\mathrm{AGc}-\mathrm{AGp}}{G\max }\right|\&times;\frac{G\max }{\mathrm{Max}-\mathrm{Min}},$

Wherein, AGc is the average gray of present frame, and AGp is the average gray of previous frame, and Gmax is the maximum gradation value that can be shown, and Sp is the slope of previous picture signal, and Max is the maximum gray scale of present frame, and Min is the minimal gray of present frame.

24, display device as claimed in claim 23, wherein, conversion is by D '=(D-Min) Sc+Min definition, and wherein, D is the present image signal, and D ' is an output image signal.

Images